how to drive a DVDrom Motor with 4 wires

Other Hardware Motors, Mechanics, Power and CNC
1

Hello, I've finished DC circuits subject as well as AC 2 years ago :sleeping:, and I've searched many articles regarding how to control/drive/etc a brushless motor from CD/DVDrom. I've seen WYE-DELTA conversion,blablabla,3phase motor,etc...
I just can't understand these all :disappointed_relieved:

Okay, so here it goes, I have here a 4-wire Brushless MOTOR from my DVDrom, I just disassembled it this morning and I don't know how to make it work. I've seen many websites discussing about DVD/CDrom motor but most of them are 11,12,3 wires. Mine is 4 wires.

My question is:
IS there a very simple guide to drive this 4-wire motor of mine?

purpose:
I will be using it to be the motor of my Arduino Rotating Led Matrix Display (otherwise known as POV).
here are the photos of my motor:


2

Generally speaking, these motors are 3-phase DC and have 3 wires. In the instance of cd-rom or dvd-rom motors, it's not unusual for them to include a hall-effect sensor such that the RPM may be accurately monitored and controlled, as is required for each of these two applications.

You've no doubt seen many of the references in literature discussing hobby R/C motors for electric models. The quickest and easiest way to interface to these motors is to grab a commercial ESC (electronic speed controller) from your parts box and hook-up it's 3 outputs. Unfortunately, ESCs are not the sort of thing that most can just reach into their parts box to grab.

In that instance, you've basically got two options.

  1. Buy an ESC from HobbyKing or Ebay
  2. Try to constuct one using mosfets and a microcontroller.

Option #2 is far, far from trivial - though mind-bendingly tempting. :slight_smile:

Here's a couple of pages you may find of use:
BLDC controller - RC Groups (BrushLessDirectCurrent controller)
http://www.flyelectric.ukgateway.net/avr_ff_timer.htm - modifying a Turnigy Plush 6A ESC to provide a timer function.

The first will be filled with more theory and a from-scratch implementation. The second, describes altering the firmware of an existing (sub $10) product so that the motor will not run for a period greater than selected (good for free-flight comps)
The second provides (reasonably) brief code that can be used as a study and starting point for your own project. There's also a thread or two around here on a hand-made BLDC shield.

This field is a lot of fun. You should be aware that you can buy a 100 W motor and a controller for it for a total of under $20. Neither of these however, can provide the satisfaction that DIY with a salvaged part can give. :slight_smile:

3

Hello, Thanks really for your reply! It helps!!!! BUT, my motor has 4 wires, you said generally motors in CDrom have 3 wires. Uhmm it is not important though... Going on, ESC is so expensive :grin:
Anyways, I saw a video on youtube which shows how to drive this motor. The maker did cut the driver board of his CDrom so that the Driver Chip remains.

I got now my driver board and my problem now is this: How am I suppose to power it up? The port is SATA. Can't I just use a 500mA AC-DC Adapter with 1.3 or so volts up to 12VDC? and hook it up to SATA Power Converter? I mean the 4wire-then POWER source of the then HDDs/CDROMS to SATA converter.


4

Glad the info has some use to you.

I would expect the 4th wire to be connected to a hall-effect sensor. Though, there are many, many RC enthusiasts that have disected the motors and discussed driving them ad-nauseum. You should be able to find some info written by a clever individual.

The thing with cd-rom motors is that they (if I remember correctly) can draw as much as 30W - yes! that is in standard, not re-wound configuration.

I would measure the resistance in the motors coils - using the lowest value you can obtain as the figure used to calculate power-draw. This will be an over-simplification - one that assumes power is connected through a coil 100% of the time and (2) that the motor is a pure resistive load - it fails to take account of the inductive nature of the windings, and the effect on instantaneous and average power consumption.

I realize money doesn't grow on trees, really I do! This is (very nearly) the cheapest ESC hobbyking has. You can buy ESCs for 50c cheaper, but they are 8-10Amps, this one will handle 15-18A. You may be able to buy one including delivery cheaper from DX.com AlliExpress or Ebay, I don't know.
AUD $6.50 - Radio Control Planes, Drones, Cars, FPV, Quadcopters and more - Hobbyking

I do know I've shared the same interest and aim in the past, having put it off for another 10 years or so. Instead, using commercially available speed controllers and motors.

Rewinding a cd-rom motor is a pretty trivial task, provided you have wire of the suitable thickness and keep your wits about you. Doing this would allow you to know with certainty if the motor was delta or wye terminated. It would also remove the ambiguity that the 4th wire provides.

Oh, and to answer your question regarding the sata power converter and a 1.3 - 12v wall-wart, this may work, but you also might make the magic smoke come out! I've had a 15A short-circuit through motors before. By the time I get there the varnish on the windings has long since turned to smoke and the motor is too hot to touch. There was probably 150W or so heating the motor. The ESC didn't even get hot enough to melt the heat-shrink. I've since rewound the motor (twice!) and used+crashed it many, many times. ESCs aren't dirt-cheap or free - they are surprisingly resilient in fault-conditions. For me, the price was far, far, far outweighed by the potential for damage to other equipment

Sorry I can't help further. :.

5

thank you sir for your effort! I've learned many things Thanks!
I think I should rather go to an ordinary DC motor for my project. The reason why I was pushing myself for this CDROM Motor is that I know it is so fast and has a high torque.

glenn

6

It may have 4 wires because it is a 2 phase stepper motor. In which case you will need a stepper driver for it.

If the motor has any markings, try googling them.

eg:

  1. CD ROM drive motor
    AVR Bipolar Stepper motor from CD-ROM driven by AtTiny2313 and L293DNE - YouTube

  2. From ebay: http://www.ebay.com.au/itm/2pcs-new-2-phase-4-wire-stepper-motor-micro-Filament-pole-stepper-motor-/151050922884?pt=LH_DefaultDomain_0&hash=item232b562b84

7

Hello sir! I've posted my motor's photos. Look, I think it is not a stepper motor. There are two kinds of motor inside a CDrom, right? :slight_smile:
Anyways, thanks for the info. I really should go to the ordinary DC motor for my proj.
glenn

8

I don't think it is a stepper Motor. The fourth solderpoint could be the "wye" -joint. If I'm right, there would be one solderpoint, that has three wires soldered to, while the others have only one wire connected...

If you decide to buy an esc from hobbyking, don't forget to order a servo-tester as well . Otherwise the esc won't do anything. ( despite you have an RC-Transmitter :wink: )

9

o_lampe:
If you decide to buy an esc from hobbyking, don't forget to order a servo-tester as well . Otherwise the esc won't do anything. ( despite you have an RC-Transmitter :wink: )

Er, my Arduino and the Servo library beg to differ! Furthermore, you can bit-bang out the required pulse (1-2ms every 20ms) with reasonably little effort.

10

o_lampe:
I don't think it is a stepper Motor. The fourth solderpoint could be the "wye" -joint. If I'm right, there would be one solderpoint, that has three wires soldered to, while the others have only one wire connected...

Sounds plausible, but first step needed is to get that multimeter out and measure the winding
resistances, that will tell you how its wired, as like as not.

11

Hi
After similar research on the web, I found at Driving a three-phase brushless DC motor with Arduino - Part 1. Theory
a very clear explanation about BDLC motors